Ability to Determine Dynamic Respiratory Parameters Evaluated during Forced Vital Capacity Maneuver Using Impedance Pneumography

Abstract

Flow-volume loops are used to calculate dynamic respiratory parameters. We examined whether our newly developed impedance pneumograph is able to measure properly respiratory parameters during Forced Vital Capacity (FVC) maneuver. Impedance measurements were performed using an electrode configuration known for providing good linearity between impedance pneumography (IP) and pneumo-tachometry (PNT) signals. The tests were performed on a group of 14 young volunteers (11 male and 3 female) without symptoms of respiratory dysfunctions. The volume-related signal from impedance pneumography and airflow signal from the reference method, pneumotachometry, were recorded. The IP signal was converted into volume units using a transfer function determined during calibration, and flow-volume loops for IP and PNT were obtained. Their shapes were compared using modified Mahalanobis distance metrics. Additionally, we compared the ratio of time of peak expiratory flow (PEF) to total expiratory time (T_TPEF/T_E) and that of volume at PEF to maximal volume (V_TPEF/V_E). The differences between these parameters, obtained for pneumotachometry and impedance pneumography, were statistically insignificant.